Dual protection inner seal washer for electromagnetic effects (eme) fasteners

A fastener system comprising:

• a fastener having a head, a shaft and a threaded end, said shaft and threaded end configured to be received in a hole in a structure;
• a nut received on the threaded end
• a first dual protection inner seal washer, received on the shaft intermediate the head and a first surface of the structure, having
• a radially outward metallic portion with a dielectric coating;
• a radially inward polymeric portion engaging the radially outward metallic portion at an interface with an interference fit, said radially inward polymeric portion having a tapering compression surface to engage the first surface proximate the hole and having a fastener element contact surface to engage a mating surface on the fastener head;
• a second dual protection inner seal washer, received on the shaft intermediate a second surface of the structure and the nut, having
• a radially outward metallic portion with a dielectric coating;
• a radially inward polymeric portion engaging the metallic portion at an interface with an interference fit, said polymeric portion having a first tapering compression surface to engage a surface of a structure proximate the hole and a second tapering compression surface to engage a surface of the nut;
• wherein torqueing of the fastener and nut compresses the tapering compression surface of the first dual protection inner seal washer and the first and second tapering compression surfaces of the second dual protection inner seal washer, inducing a predetermined pressure in the radially inward polymeric portion of the first dual protection inner seal washer and the radially inward polymeric portion of the second dual protection inner seal washer in a joint created by the fastener, nut and structure.

A method for enhanced electromagnetic effects protection in a joint, said

• method comprising:
• inserting a fastener through a fastener side dual protection inner seal washer having a radially outward metallic portion and a radially inward polymeric portion with at least one compression surface and an engagement surface to engage the fastener;
• inserting a shaft of the fastener into a hole in a structure, the dual protection inner seal washer engaging a first surface of the structure adjacent the hole with the compression surface;
• receiving a nut side dual protection inner seal washer having a radially outward metallic portion and a radially inward polymeric portion with a first compression surface and a second compression surface over a threaded end of the fastener with the first compression surface engaging a second surface of the structure adjacent the hole;
• receiving a nut on the threaded end of the fastener engaging the second compression surface;
• torqueing the nut and fastener to compress the at least one compression surface of the fastener side dual protection inner seal washer and the first and second compression surfaces of the nut side dual protection inner seal washer to create a predetermined increased pressure in the joint.